Denver (CNN) -- A man suspected of planting a bomb at a mall in Littleton, Colorado, on the 12th anniversary of the attack at Columbine High School was arrested Tuesday at a grocery store in Boulder, authorities said.

Earl Albert Moore was taken into custody at a King Soopers grocery store after customers and employees noticed a man they "deemed suspicious," Jefferson County Sheriff Ted Mink told reporters at an afternoon press briefing outside the Denver office of the Federal Bureau of Investigation.

The arrest brought to an end a search that began last week after a pipe bomb was discovered on April 20 in a back hallway at the Southwest Plaza Mall, just a few miles from the high school where Eric Harris and Dylan Klebold killed more than a dozen people before committing suicide.

The discovery of the bomb at the mall sent a ripple of fear through the community, which was marking the 12th anniversary of the rampage at Columbine. Dozens of Jefferson County schools were locked down.

But authorities ruled out any connection between the bomb at the mall and the Columbine anniversary.

"This incident had no bearing on any of the schools in the Littleton school district," Mink told reporters. "There was absolutely no connection."

Police took Moore into custody at the grocery store Tuesday morning, said Boulder police spokeswoman Kim Kobel. Moore, who was turned over to federal authorities, was scheduled to appear in federal court in Denver on Wednesday, FBI Special Agent Jim Yacone said at the news conference.

Authorities did not take questions at the brief news conference. It was not immediately known what federal charges Moore would face for allegedly planting the bomb.

Moore allegedly planted the bomb at the mall just one week after he was released from the medium-security Federal Correctional Institution in Estill, South Carolina, authorities said. A federal law enforcement source told CNN Sunday that Moore was serving time for bank robbery when he was released.

Federal court records show Moore was sentenced to 18 years in prison for a March 2005 robbery at the Whitesville State Bank in Crab Orchard, West Virginia.

Prosecutors asked later for Moore's sentence to be reduced to reflect "defendant's subsequent substantial assistance in investigating or prosecuting another person."